It is evident that oxygen carriers play a pivotal role in the chemical looping combustion.Although the majority of studies have concentrated on enhancing the high-temperature thermal stability and reactivity of oxygen...It is evident that oxygen carriers play a pivotal role in the chemical looping combustion.Although the majority of studies have concentrated on enhancing the high-temperature thermal stability and reactivity of oxygen carriers,it is imperative to study the attrition behaviors of oxygen carriers precisely.In this work,a micro fluidized bed thermogravimetric analysis(MFB-TGA)was developed to obtain the attrition properties through real-time measurement of weight changes during the redox reactions.Ilmenite,iron ore,and laterite ore were selected as the oxygen carriers,and the contributions of mechanical,thermal,and chemical stresses to oxygen carrier attrition were investigated.It was found that ilmenite and iron ore started stable attrition just after the 20th and 5th cycles due to the activation phenomenon.Laterite ore suffered a fast attrition stage with a rate of 0.37%h^(−1)before the 20th cycle,after that,the attrition rate changed to be slow.At the end of activation,ilmenite and iron ore attrition was led by mechanical stress with the proportion of∼40%,while chemical stress was the predominant factor of laterite ore attrition with the proportion of∼57.6%.The proposed micro fluidized bed thermogravimetric method provides an effective and convenient pathway to determine,evaluate,and compare the attrition behavior of oxygen carriers in laboratory.展开更多
The characteristics and kinetics of coal and oil shale pyrolysis were comparatively studied by using a micro fluidized bed reaction analyzer(MFBRA).The isothermal differential model was first applied to calculate the ...The characteristics and kinetics of coal and oil shale pyrolysis were comparatively studied by using a micro fluidized bed reaction analyzer(MFBRA).The isothermal differential model was first applied to calculate the kinetic parameters of activation energy and frequency factor according to the major gas components during pyrolysis.The results showed that the major gas components released from coal and oil shale under the isothermal condition had different initiating and ending time points,and the difference was more significant under the programmed heating conditions.The shrinking core model allowed better fitting relevance for the coal pyrolysis,while the three-dimension model was more suitable for oil shale pyrolysis,indicating that the gases from the pyrolysis process of coal and oil shale might go through different reaction paths.The activation energy of oil shale pyrolysis was 36.96 kJ·mol^(−1),larger than the value of pyrolysis of the two coals,which was 21.16 and 32.17 kJ·mol^(−1),respectively.The above results justified that the oil shale pyrolysis with high ash contents was somehow more difficult to take place in terms of higher activation energy and the MFBRA could be a useful tool to give some insight into the intrinsic kinetics and reaction mechanisms of coal and oil shale pyrolysis.展开更多
Fuel conversion and clean energy reaction systems involve a variety of catalytic and non-catalytic gas-solid thermochemical reactions.A good understanding of the correct reaction mechanism and kinetics,as well as the ...Fuel conversion and clean energy reaction systems involve a variety of catalytic and non-catalytic gas-solid thermochemical reactions.A good understanding of the correct reaction mechanism and kinetics,as well as the profiles of reaction products,is of great significance to the development,design,and operation of such reaction systems.The micro fluidized bed reaction analysis provides an efficient and reliable method to acquire this essential information with low capital and operating costs,low energy consumption and enhanced safety.This paper provides an overview of the system and its characteristics for the micro fluidized bed reaction analyzer that has been well proven to be a reliable new approach as well as an instrument for characterizing various gas-solid thermochemical reactions.展开更多
This study utilizes a combination of micro fluidized bed analysis technology and isotope-tagging methodology to investigate the decomposition of carbonate ores in CO_(2) atmospheres.Utilizing the decomposition of magn...This study utilizes a combination of micro fluidized bed analysis technology and isotope-tagging methodology to investigate the decomposition of carbonate ores in CO_(2) atmospheres.Utilizing the decomposition of magnesite in an atmosphere containing ^(13)CO_(2) as a case study,the reaction behavior and kinetics were investigated using a micro fluidized bed reaction analyzer(MFBRA).The results reveal that ^(13)CO_(2) in the atmosphere hinders the decomposition process,thereby increasing the time required for complete decomposition.The activation energy was observed to increase with the concentration of ^(13)CO_(2) in the reaction atmosphere.Compared to the results obtained from thermogravimetric analysis(TG),the activation energy and pre-exponential factor values deter-mined by the MFBRA are lower.Due to the excessive suppression caused by the accumulation of product gas within the sample crucible,the apparent activation energy calculated based on TG data was overestimated,particularly in atmospheres containing the product gas CO_(2).The MFBRA,operating in an environment char-acterized by essentially eliminated external gas diffusion,extensive gas-solid mixing,and high rates of mass and heat transfer,has proven to be highly capable of accurately determining the kinetics of carbonate ore decom-position in CO_(2)-rich atmospheres.This study provides a straightforward and reliable method for elucidating the reaction characteristics and kinetics of carbonate ore decomposition in atmosphere of CO_(2).展开更多
基金supported by the National Key R&D Program of China(grant No.2024YFB4106000).
文摘It is evident that oxygen carriers play a pivotal role in the chemical looping combustion.Although the majority of studies have concentrated on enhancing the high-temperature thermal stability and reactivity of oxygen carriers,it is imperative to study the attrition behaviors of oxygen carriers precisely.In this work,a micro fluidized bed thermogravimetric analysis(MFB-TGA)was developed to obtain the attrition properties through real-time measurement of weight changes during the redox reactions.Ilmenite,iron ore,and laterite ore were selected as the oxygen carriers,and the contributions of mechanical,thermal,and chemical stresses to oxygen carrier attrition were investigated.It was found that ilmenite and iron ore started stable attrition just after the 20th and 5th cycles due to the activation phenomenon.Laterite ore suffered a fast attrition stage with a rate of 0.37%h^(−1)before the 20th cycle,after that,the attrition rate changed to be slow.At the end of activation,ilmenite and iron ore attrition was led by mechanical stress with the proportion of∼40%,while chemical stress was the predominant factor of laterite ore attrition with the proportion of∼57.6%.The proposed micro fluidized bed thermogravimetric method provides an effective and convenient pathway to determine,evaluate,and compare the attrition behavior of oxygen carriers in laboratory.
基金The study was conducted with the research programs financed by the National Natural Science Foundation of China(U1862107,21406264)Science Foundation of China University of Petroleum-Beijing(Grant No.2462018BJC003)R&D Program of China National Petroleum Corporation(LH-17-08-55-05).
文摘The characteristics and kinetics of coal and oil shale pyrolysis were comparatively studied by using a micro fluidized bed reaction analyzer(MFBRA).The isothermal differential model was first applied to calculate the kinetic parameters of activation energy and frequency factor according to the major gas components during pyrolysis.The results showed that the major gas components released from coal and oil shale under the isothermal condition had different initiating and ending time points,and the difference was more significant under the programmed heating conditions.The shrinking core model allowed better fitting relevance for the coal pyrolysis,while the three-dimension model was more suitable for oil shale pyrolysis,indicating that the gases from the pyrolysis process of coal and oil shale might go through different reaction paths.The activation energy of oil shale pyrolysis was 36.96 kJ·mol^(−1),larger than the value of pyrolysis of the two coals,which was 21.16 and 32.17 kJ·mol^(−1),respectively.The above results justified that the oil shale pyrolysis with high ash contents was somehow more difficult to take place in terms of higher activation energy and the MFBRA could be a useful tool to give some insight into the intrinsic kinetics and reaction mechanisms of coal and oil shale pyrolysis.
基金the financial supports of the Ministry of Science and Technology of People’s Republic of China(2018YFE0103400)the National Natural Science Foundation of China(U1908201).
文摘Fuel conversion and clean energy reaction systems involve a variety of catalytic and non-catalytic gas-solid thermochemical reactions.A good understanding of the correct reaction mechanism and kinetics,as well as the profiles of reaction products,is of great significance to the development,design,and operation of such reaction systems.The micro fluidized bed reaction analysis provides an efficient and reliable method to acquire this essential information with low capital and operating costs,low energy consumption and enhanced safety.This paper provides an overview of the system and its characteristics for the micro fluidized bed reaction analyzer that has been well proven to be a reliable new approach as well as an instrument for characterizing various gas-solid thermochemical reactions.
基金the financial backing received from the Ministry of Science and Technology of the People’s Republic of China(No.2022YFF0705100)the National Natural Science Foundation of China(U1908201)Natural Science Foun-dation of Liaoning Province(JYTMS20231496).
文摘This study utilizes a combination of micro fluidized bed analysis technology and isotope-tagging methodology to investigate the decomposition of carbonate ores in CO_(2) atmospheres.Utilizing the decomposition of magnesite in an atmosphere containing ^(13)CO_(2) as a case study,the reaction behavior and kinetics were investigated using a micro fluidized bed reaction analyzer(MFBRA).The results reveal that ^(13)CO_(2) in the atmosphere hinders the decomposition process,thereby increasing the time required for complete decomposition.The activation energy was observed to increase with the concentration of ^(13)CO_(2) in the reaction atmosphere.Compared to the results obtained from thermogravimetric analysis(TG),the activation energy and pre-exponential factor values deter-mined by the MFBRA are lower.Due to the excessive suppression caused by the accumulation of product gas within the sample crucible,the apparent activation energy calculated based on TG data was overestimated,particularly in atmospheres containing the product gas CO_(2).The MFBRA,operating in an environment char-acterized by essentially eliminated external gas diffusion,extensive gas-solid mixing,and high rates of mass and heat transfer,has proven to be highly capable of accurately determining the kinetics of carbonate ore decom-position in CO_(2)-rich atmospheres.This study provides a straightforward and reliable method for elucidating the reaction characteristics and kinetics of carbonate ore decomposition in atmosphere of CO_(2).
